The present invention is directed generally to photoresponsive imaging members, and more specifically to photoconductive imaging members comprised of certain fluorinated trisazo photogenerating pigments. In one embodiment the trisazo photogenerating pigments are obtained from trisaminoaryl amines. One embodiment of the present invention is directed to an imaging member comprised of a supporting substrate, a photogenerating layer comprised of a fluorinated triazo photogenerating pigment in contact therewith, and a charge, especially hole transport layer. Imaging members with the fluorinated trisazo photogenerating pigments of the present invention are sensitive to wavelengths of from about 400 to about 800 nanometers, that is from the visible region to the near infrared wavelength region of the light spectrum. Moreover, in embodiments thereof the imaging members of the present invention possess low dark decay characteristics as illustrated herein.
Photoresponsive imaging members are known, such as those comprised of a homogeneous layer of a single material such as vitreous selenium, or composite layered devices containing a dispersion of a photoconductive composition. An example of a composite xerographic photoconductive member is described in U.S. Pat. No. 3,121,006, which discloses finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. Imaging members prepared according to the teachings of this patent contain a binder layer with particles of zinc oxide uniformly dispersed therein coated on a paper backing. The binders disclosed in this patent include materials such as polycarbonate resins, polyester resins, polyamide resins, and the like, which are incapable of transporting injected charge carriers generated by the photoconductive particles for any significant distance.
Photoreceptor materials comprising inorganic or organic materials wherein the charge generating and charge transport functions are performed by discrete contiguous layers are also known. Additionally, layered photoreceptor members are disclosed in the prior art, including photoreceptors having an overcoat layer of an electrically insulating polymeric material. Other layered photoresponsive devices have been disclosed, including those comprising separate photogenerating layers and charge transport layers as described in U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Photoresponsive materials containing a hole injecting layer overcoated with a hole transport layer, followed by an overcoating of a photogenerating layer, and a top coating of an insulating organic resin, are disclosed in U.S. Pat. No. 4,251,612, the disclosure of which is totally incorporated herein by reference. Examples of photogenerating layers disclosed in these patents include trigonal selenium and phthalocyanines, while examples of transport layers include certain aryl diamines as illustrated therein.
U.S. Pat. No. 3,574,181 discloses disazo compounds useful as coloring agents. Composite electrophotographic photosensitve materials containing various azo compounds are disclosed in U.S. Pat. No. 4,618,672, wherein bisazo compounds particularly suitable for use in the charge generating layer of a layered electrophotographic photoconductor are illustrated. Similarly, an article by M. Hashimoto entitled "Electrophotographic Sensitivity of Fluorenone Bisazo Pigments", Electrophotography, Vol. 25, No. 3 (1986), discloses disazo compounds as charge generating materials in electrophotographic layered photoreceptors. Further, Japanese Patent Kokai No. 54-20736 discloses disazo pigments as constituents in electrophotographic processes. Japanese Patent 58-177955 also discloses many disazo compounds suitable for use in the photosensitive layer of an electrophotographic device.
U.S. Pat. No. 4,713,307, the disclosure of which is hereby totally incorporated by reference, also discloses photoconductive imaging members containing a supporting substrate, certain azo pigments as photogenerating materials, and a hole transport layer that preferably contains an aryl diamine compound dispersed in an inactive resinous binder.
U.S. Pat. No. 4,797,337, the disclosure of which is totally incorporated herein by reference, discloses a photoconductive imaging member comprising a supporting substrate, a hole transport layer, and a photogenerating layer comprising specific disazo compounds.
Documents illustrating layered organic electrophotographic photoconductor elements with azo, bisazo, and related compounds include U.S. Pat. Nos. 4,390,611, 4,551,404, 4,596,754, Japanese Patent 60-64354, U.S. Pat. Nos. 4,400,455, 4,390,608, 4,327,168, 4,299,896, 4,314,015, 4,486,522, 4,486,519, 4,555,667, 4,440,845, 4,486,800, 4,309,611, 4,418,133, 4,293,628, 4,427,753, 4,495,264, 4,359,513, 3,898,084, 4,830,944, 4,820,602, and 3,898,084; Electrophotography, K. Ota, 25, 30, 303, (1986), Japanese 62-139308 (1987), and Japanese Patent Publication 60-111247. With the invention of the present application there are selected for the imaging members certain fluorinated trisazo photogenerating pigments obtained from tris(p-aminophenyl)amine and carbazole couplers, which pigments are sensitive to wavelengths of light of from about 400 to about 800 nanometers, thereby permitting the photoconductive imaging members with these pigments to be selected for infrared printers, LED printers, and electrophotographic imaging processes, and the like.
U.S. Pat. No. 4,424,266 discloses an electrophotographic photosensitive element having a conductive support and a photosensitive layer comprising a carrier generating phase layer containing a carrier generating material selected from the group consisting of perylene dyes, polycyclic quinones, and azo dyes, and a carrier transporting phase layer containing a hydrazone carrier transporting material. The carrier generator materials can be used either singly or in combination.
Japanese Patent Publication J01-198-763 discloses an electrophotographic photoreceptor containing a bisazo series compound in a photosensitive layer formed on a conductive support. A charge transport material is used with the bisazo pigment as a charge generation material, such as 2,4,7-trinitrofluorenone, tetracyanoquinodimethane, carbazole, triarylalkane derivatives, phenylenediamine derivatives, hydrazone compounds, or stilbene derivatives.
In a patentability search report there are recited the following U.S. Pat. Nos. 4,507,471 which discloses certain trisazo compounds, see column 2 for example, which compounds can be used for developing charge carrier generating compounds which are highly sensitive and have a uniform sensitivity throughout the visible region; and 4,916,039 and 4,925,758 which disclose a photoconductive layer comprising the azo pigments as illustrated, for example, in column 3; also disclosed as a starting material for preparing the azo pigments is a 2-hydroxy-3-carbamoylbenzo(a)carbazole derivative.
There is illustrated in U.S. Pat. No. 5,175,258, a process for the preparation of bisazo photogenerating pigments which comprises the reaction of diaminofluorenone with sodium nitrite, hydrochloric acid, and fluoroboric acid; thereafter reacting the resulting product with an anilide coupler; and subsequently annealing the product obtained; U.S. Pat. No. 5,139,910 bisazo compounds essentially as represented by the formula of FIG. 9 wherein Cp is an azoic coupler such as 2-hydroxy-3-naphtho-o-methoxyanilide; 2-hydroxy-3-naphtho-p-methoxyanilide; 2-hydroxy-3-naphtho-p-trifluoromethy lanilide; 2-hydroxy-3-naphtho-o-methylanilide; 2-hydroxy-3-naphtho-p-chloroanilide; 2-hydroxy-3-naphtho-p-methylanilide; 2-hydroxy-3-naphtho-p-fluoroanilide; 2-hydroxy-3-naphtho-o-chloroanilide; 2-hydroxy-3-naphtho-m-trifluoromethylanilide; 2-hydroxy-3-naphtho-p-nitroanilide; 2-hydroxy-3-naphtho-o-ethylanilide; 2-hydroxy-3-naphtho-o-fluoroanilide; 2-hydroxy-3-naphtho-p-bromoanilide; and the like, and photoconductive imaging members thereof; and U.S. Pat. No. 5,130,443. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
Although the prior art imaging members are suitable for their intended purposes, a need remains for imaging members containing certain trisazo materials. In addition, a need exists for imaging members containing photoconductive materials with improved photoconductivity. There is also a need for imaging members with photoconductive materials comprised of fluorinated trisazo photogenerating pigments, wherein the material has enhanced dispersability in polymers and solvents. Further, there is a need for photoconductive materials with enhanced dispersability in polymers and solvents that enable low cost coating processes in the manufacture of photoconductive imaging members. Additionally, there is a need for photoconductive materials that enable imaging members with enhanced photosensitivity in the red and infrared wavelength regions of the light spectrum enabling the resulting imaging members thereof to be selected for LED xerographic imaging processes and printers, and diode laser printer and imaging apparatuses. There remains a need for trisazo compounds for improved xerographic performance. The fluorinated trisazo pigments of the present invention described herein are directed toward achieving these needs.